1. Field of the Invention
The present invention relates to a scanning controller, a scanning apparatus and a method for performing the scanning controller, and more particularly, to a scanning controller for diminishing incompletion or discreteness of scanned data.
2. Description of the Prior Art
During a single side or double side scanning process performed by typical image scanner, it usually occurs that an image buffer of the scanner overflows with or is full of catching an overlarge image data amount if the typical image scanner adopts a multiple-page or a high-resolution scanning mode. As long as available capacity of the image buffer is insufficient to continue store following-scanned image data thereon, the scanning-document process of the image scanner would be interrupted. For example, an image sensor of the image scanner such as a charge coupled device (CCD) or a contact image sensor (CIS) is stopped to scanning, and a stepping motor is stopped to drive a transmission mechanism of the image scanner.
In an exemplar that a scanning-document process as showing in FIG. 1 is performed by the typical image scanner and includes the following steps of:
step S100, scanning at least one page of a document;
step S110, determining whether the image buffer is full of data or not, wherein if not yet, performing a step S120, and otherwise if so, performing a step S130;
step S120, continuing to scan this page;
step S130, stopping scanning of an image sensor of the image scanner and stopping driving movement of a stepping motor, and then performing a step S132;
step S132, determining whether the image buffer is full of data or not, wherein if not yet, performing a step S134, and otherwise if so, performing the step S130;
step S134, reactivating scanning and driving the stepping motor;
step S140, determining whether the scan to this page is finished or not, wherein if so, performing a step S150, and otherwise if not, returning to the step S110 so as to determining whether the image buffer is full of data or not; and
step S150, determining whether the scans to all of the pages of the document are finished or not, wherein if so, ending this process, and otherwise if not, returning to the step S100 so as to scan the next page.
On the above-mentioned step S130, although the image sensor of the image scanner is controlled to stop scanning and to stop driving movement of the stepping motor, the fact is that the inertia still carries the stepping motor and its transmission mechanism under a high-speed (e.g. in a full step) running to gradually decelerate for a while until completely stop, rather than instantly stop. Briefly, during such a decelerated period, the stepping motor and its transmission mechanism still move to a wrong position in excess of where the stepping motor and its transmission mechanism are supposed to stop with regard to the scanned document. The image data on the excess can not be catch by the image sensor. Afterward, when the image data amount stored within the image buffer falls down, the stepping motor and its transmission mechanism are reactivated to move from the wrong position for scanning. It would invoke incompletion or discreteness of some image data scanned during the scanning-document process as a data loss problem. To resolve such a problem, an approach is to enlarge image buffer capacity with a higher element expense but could not bring an economic benefit.